AudiSport's view on this is much the same as a lot of people, however bear in mind that those are not especially fair comparisons: the A3/TT are NOT full Quattro (they're Haldex) - the A4 is permanent (Torsen) Quattro, so feels even more planted mid-corner and/or when rear traction starts to break.
In the TT/A3, you're lugging all that extra running gear around with you without the immediate Quattro benefits that you get in an A4, so there's even less in favour of Quattro on the smaller cars.
If anything I'm even more in favour of a Quattro now after a weekend spent out in the countryside where I had to repeatedly accelerate out of a tiny gravel side-road and UP onto a busy A-road (ferrying people between the cottage and the local train station)... there was a BMW 3-series and an Astra that were both making an utter meal of it each time... no such problem for the Quattro
Was even tempted to take the traction control off at one stage to add to the "fun"
All depends what you want: the 2WD will be lighter, so more frugal and more fun, the Quattro will be quicker off the line if the surface is in any way compromised (i.e. damp) and you'll be able to control higher speed in the corners.... so more capable.
Personally? I'd definitely go for the Quattro and then start tweaking as and when I wanted more power - a remap to 180bhp-ish at least (it's the same underlying engine - just with only one intercooler)... but the FWD is still a stunning car, so I'm certainly not going to slate it!